Having problems on Start-Up - Kicks to Command Line?

Just installed Ubuntu 12.10 for the first time on a new AMD desktop tower. Was working fine for the first day or so. Opened the case to install an internal card reader, and upon startup instead of booting the GUI OS it boots the command line prompt. Tried removing the card reader but still getting command line on startup. At the risk of sounding like a total n00b , I am already kindof lost.